Abstract: Bacteria of natural waters have an important role in recycling nutrients. As we accumulate information on the biomass of bacteria, however, we realize that these large quantities of bacteria may also be an important source of particulate matter for animals. While these statements have been made before, there have been few attempts to quantify the role of bacteria as producers of particulate matter in freshwater systems. The study reported here deals with biomass and production rates of bacteria in a tundra pond in arctic Alaska.